/**
 *  Copyright 2002-2009 the original author or authors.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package foo.bar.forum.utils;

import java.util.*;

/**
 * Utility to perform manipulation on a {@link Collection}.
 *
 * @see {@link Transformer}
 *
 * @author tmjee
 * @version $Date$ $Id$
 */
public class CollectionUtils {


    public static <T,F> Set<T> collect(Set<F> collection, Transformer<F,T> transformer) {
        Set<T> result = new LinkedHashSet<T>();
        for (F f : collection) {
            T t = transformer.transform(f);
            if (t != null) {
                if (t instanceof Collection) {
                    result.addAll((Collection)t);
                }
                else {
                    result.add(t);
                }
            }
        }
        return result;
    }

    public static <T,F> List<T> collect(List<F> collection, Transformer<F,T> transformer) {
        List<T> result = new ArrayList<T>();
        for (F f : collection) {
            T t = transformer.transform(f);
            if (t != null) {
                if (t instanceof Collection) {
                    result.addAll((Collection)t);
                }
                else {
                    result.add(t);
                }
            }
        }
        return result;
    }
}
